Mi 



Report of the State Geologist. 



lateral lobe, which is narrow and acute, a broad, rather low lateral saddle 

 followed below by a moderately shallow and broad, rounded umbilical lobe 

 and an acute saddle at the contact line. The form of this suture, if it has not 

 been distorted by pressure is unlike that of other species of the genus here 

 described, without varying from the gephyroceran type. 



The original example is from Homer, Cortland county, the other from the 

 vicinity of Ithaca. Both of these localities are in a region where the typical 

 Intumescens-fauna is complicated with the brachiopod faunas characterizing 

 the Ithaca series of central New York. 



GEPHYROCERAS ? ( PrOBELOCERAS V) GeNUNDEWA, Sp. UOV. 

 Plate VIII, Figs. 1-3. 



This is a small form, abundant in the Styliola limestone, and while it is 

 described as a distinct species, it actually represents an immature rmase of Pro- 

 beloceras Lutheri. This apparently irrational interpretation is justified by 

 the evidence that this form is a constant mature condition. The normal adult 

 condition of Probel. Lutheri is not known to occur in this prenuncial fauna. 



Gephyroceras Gemmdewa is, consecpiently, a small shell with a simple 

 gephyroceran suture, its form discoidal, umbilicate and ventrally grooved as 

 in Probel. Lutheri at a corresponding size. Its diameter seldom exceeds 

 8 mm. in any specimens which have shown septa. The suture of the last 

 whorl is characterized by the large lateral saddle and broad, undivided 

 umbilical lobe. This is such a shell (if smaller at maturity) as the Gon. 

 forcijnfer, Sandberger,* one of the species embraced by Hyatt among those 

 typical of the genus. While we admit its similarity to, and agreement with 

 an immature phase of Probel. Lutheri, it is proper to distinguish it by a 

 distinct specific and even generic name, for it is through such a distinct phase 

 that the shell whose mature condition and history we characterize by the name 

 I ) robel. Lutheri, passes in earlier growth. Should further investigation show 

 the presence of Probel. Lutheri in the prenuncial fauna, this form must then 

 be looked upon solely as one of its phases. Gephyroceras Gemmdewa would 

 undoubtedly have become that species, had its growth not reached its final 

 stage thus early. 



The species lias been not infrequently observed in the form of pyrite, 

 barite and sphalerite replacements in the Styliola limestone at Genundewa on 

 Canandaigua lake, at Middlesex and elsewhere. 



* See Sandberger. Verstein. d. Rhein. Scbicht. Syst. in Nassau, pi. VI. fig. 8. 



